In the deadliest attack, late on Monday, gunmen opened fire at a market in the town of Damboa, targeting local hunters who sell bush meat from animals such as monkeys and pigs, which strict Muslims are forbidden to eat, a local official said.

“Gunmen suspected to be members of BH (Islamist sect Boko Haram) came to the town market and shot dead 13 local hunters on the spot while five others died from their injuries at the hospital,” Alhaji Abba Ahmed said. “They came to the market in a Volkswagen Golf car, carried out the operation and left.”

In a separate attack in the north’s biggest city of Kano, some 500 km (310 miles) west of Damboa, on Tuesday, suspected Boko Haram members riding on motorbikes shot dead five people playing an outdoor board game, witnesses and a hospital source who received the bodies said. Two others were wounded.

Damboa is in the remote northeast, the sect’s heartland near the borders with Niger, Cameroon and Chad.